Conventionally, power-assisted chairs include a motor-operated lift mechanism for aiding persons that require assistance in entering or exiting the chair. More particularly, motor-operated lift mechanisms are interconnected between a stationary base assembly and a moveable chair frame. Alternatively, some power-assisted chairs include separate linkage mechanisms for permitting the seat occupant to selectively extend and retract a leg rest assembly and/or produce reclining angular movement between an upright first position and a reclined second position.
Power-assisted chairs may be adapted to provide the lift and tilt function in combination with a leg rest and/or reclining function. Chairs which provide such a combination of multi-positional functions generally require the use of multiple motors for driving the separate linkages, which results in extremely large and expensive chair units. In addition, most power-assisted chairs incorporate a drive mechanism that employs both a power drive function for extending the leg rest, lifting the chair, and reclining the chair, and a power return function for returning the chair to the normal seated position.
An important characteristic of power-assisted chairs is the ability to support heavy loads during the lift and tilt functions. More specifically, power-assisted chairs are designed to support individuals of a particular weight. Typically, power-assisted chairs that are adapted to support weight above a particular threshold, such as 300 pounds, require multiple motors.